Sound amplifier



Oct. 9 1923. 1,469,899

y L. H. DONNELL SOUND AMPLIFIER Filed June 19. 1922 11al IIE- E i ;Fl

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. 95 'of suitable desi Patented Oct. 9;, 1923. Y

UNITED STATES A LLoYD IIAnIL'roN DoNNELL, or ANN Aaron, MICHIGAN.

` y SOUND AMrLIrIEB.

Application sued :une 19, 1922. semi xatsasao.

To all whom it may concern .f-

Be it known that 1, LImrD HALmfroN DONNELL, a citizen of the United States, re'- siding at Ann Arbor,'in the countyof Washtena'w and State of Michigan,l have invented certain new and useful Improvements in a- Sound Amplifier, of which the following is a speciicatiomreference being had therein to the accompanying drawing.

10 This inventlon relates to an lmproved am# plifier to be used in connection with different types ofsound producing apparatuses, the same being-ca able of pratical use in conne tion with ra io phones. l

The principal object of c,the invention is to generally im rove Iupon amplifiers of this class by providlng one of extreme simplicity which is practical in construction and such that comparatively faint sounds can be converted into easil audible sounds.

More specifica ly speaking, it is another and important object of the `invention to rovide a sound amplifier or loud speaker or radiophones which embodies a chamber 4sage is arrange this passage being formed from a` stri of sheet material coiled as shown and having its innermost coil disposed opposite one or more sound intake o nings formed in the wall ofthe chamber.

i Other objects and advantages of the in` vention will be ap arent during-the course of the following dscription. y

In the accompanying drawings forming a part of this specification and in 'which like numerals are employed to designatelike gpecically described, the improved amplier preferably comprises a substantially rectangular wooden box 1 formed at its front with a comparatively` 'large discharge ings are shown, only one is necessary" As in which a convolute pasy opening 2'for the sound waves and provided before indicated,a peculiarly designed tortuous or convolute passage for the sound waves is arranged inside of this box and although this passage could be formed otherwise', it is preferably constructed from a single strip of flat sheet material 4 bent upon Itself to provide a plurality of convolutlons 5 which dually increase 1n `size toward the outer en of the passage. By providing a flat strip of metal for constructing such a passage, the walls of the convolutions are vdisposed in transverse parallelism and are uniformly spaced throughout their widths so as'not to interfere with equal distribution of the eluent sound waves. As seen more clearly in Figure 3, the innermost and smallest convolution is arranged opposite the aforesaid intake openings 3, and the end of the strip forming this small convolution or coil is spaced 'from the adjacent coil to provide the opening 5 for permitting the sound waves to enter the discharge passage.

It may be conveniently stated here, as before indicated, that the amplifier is especiallydesi ed for use in connection with a radio telep one or the like, and in the drawings, I have shown conventional types of telephonereceivers R which are connected with the felt washers 6 which are secured to the sides of the box around the aforesaid openingsB. These washers serve as simple and convenient means' for connection of the telephone receivers to the box and to pro- Particular attention is directed to the fact that in practice, the box will be composed of comparatively? soft wood and. as more clearly seen in igure 3, the space between the inner faces of the sides of the box is less than the width of the metal strip employed to forni the convolutions or sound wave passage.- @When assembling the device, the metal strip is coiled to form thev convolutions and the outerend of the strip is bent as shown at 7 and is received in the small of the 'topl of the box. Then the sldes'of the boxes are/forced onin a press, causing the edges ofthe strip to become' embedded 1n the inner' faces ofthe sides of the box. It is in this manner that the convolute metal strip isheld in place. Although it is not es- 4sential, the front wall of the box -may be groove' 8 formed in the under-faceI Aas shown in the drawing.

recessed on its inner face as indicated at 9 to accommodate that portion of the adjacent coil or convolution which bears against it.

In use, the means for conveying the sound waves into the sound amplifying box or 'hamber is associated with the aforesaid intake openings 3 and the sound is introduced into the innermost and smallest of the convolutions. and passes through the opening 5 and Vfollows the tortuous path between the wallsl ol the surrounding and the larger convolutions until it is discharged through the opening' 2 in the box. In this Way, comparatively l'aint sounds can be amplified to render them very distinct and audible at a considerable distance from the amplifier.

Hence. a small radio set can serve to amuse a number ot' persons b v simply attaching one or both of the usual ear pieces Constant use o the horn has actually1 demonstrated that the results sought can be effectively accomplished.

B v carefully considering the description in connection with the drawings, persons familia r `with devices of this class will doubtless be able to obtain a clear understanding o t' the invention. Therefore. a '-iore lengthy and dctrillcd description is :ll-med unneclblr'l...

Since probably the best results may be obtained with the construction and arrangement herein shown and described, this is taken as the preferred embodiment of the invention. However. it is to be understood that minor changes coming' within the scope ol' tbe invention as claimed may be resorted to it' desired.

I claim:

l. A sound amplifier for sound reproducing apparatuses comprising a flat strip of material coiled to form a convolute passage between its coils, the innermost coil being comparatively small and the surrounding coils gradually increasing in size toward the outer coil to render the passage of gradually increasing.,r area from its inner toward its outer end, and a pair of spaced vertical plates engaging-the edges of the coils and closing the passage at opposite sides to compel the sound waves to travel from end to end. one of said plates having an opening formed therein opposite one end of the innermost coil to permit the reproduced Waves to enter' the passage for amplification.

Q. A sound amplifier for use in connection with sound producing apparatuses comprising a substantially rectangular box having a,relati vely large discharge opening in its front side and a comparatively small sound intake opening at the center of one of its vertical sides, a flat strip of sheet material arranged inside of the box and having one end connected with the top wall of the box, the opposite end of the stripV being bent upon itself to provide a plurality of closely spaced convolutions, the inner one of which has its open end communicating with the aforesaid opening, said strip of material being of a width greater than the distance between the Walls of the box and having its edges embedded in the inner faces of said wall.

In testimony whereof I hereunto affix my signature.

LLOYD HAMILTON DONNELL. 

